This invention relates to a hot-melt adhesive composition having highly improved adhesivity.
In view of its superior adhesive power, an ethylene-vinyl acetate copolymer or a hydrolyzed copolymer thereof has already been used as a component for a hot-melt adhesive composition. For instance, Japanese Pat. publication No. 37488/1977 Specification discloses a hot-melt adhesive composition containing a hydrolyzed ethylene-vinyl acetate copolymer, waxes and tackifying resins such as rosine. However, such hitherto known hot-melt adhesive copositions do not always provide satisfactory adhesive power.
To overcome the disadvantage, the present inventors conducted studies and succeeded in obtaining a hot-melt adhesive composition having a considerably increased adhesive power by using a hydrolyzed ethylene-vinyl acetate copolymer with a degree of hydrolysis not less than 50% to the acetate groups in the copolymer and/or a carboxyl-containing product obtained by grafting said hydrolyzed copolymer with carboxyl-containing unsaturated monomers, in combination with a tackifying resin in a specified ratio.